11 things you didn’t know were contagious

Contagion is everywhere

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Germs aren’t the only things you have to worry about “catching.”

Restaurant orders

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Diners are happier when they order entrées that are similar nutritionally to those of their companions, found University of Illinois research. If you’re watching your waistline, place your order first so you’re not tempted by your pals’ cravings.

Negative thinking

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University students who were randomly paired with roommates highly prone to brooding were likely to “catch” their negative-thinking style after only three months, found a University of Notre Dame study. Recognise that other people may influence how you respond to life’s challenges.

Happiness

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On the other hand, positive feelings also rub off, according to a seminal study of almost 5,000 people by researchers at Harvard and the University of California, San Diego. When you feel happy, a friend who lives within one mile is 25 percent more likely to feel happy, and neighbours are 34 percent more likely to feel happy. The same data found that an extra $5,000 increased happiness by about 2 percent, a much lower impact than what’s gained by having a joyful friend of a friend (a second-degree connection), which can boost your own good feelings by 10 percent.

Quitting smoking

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The same research team found that when one person quit smoking, close friends and family members became 36 percent less likely to smoke. The ripple effect: Even very casual acquaintances of the initial quitter became 20 percent less likely to light up.

Stress

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The brain is hardwired to detect stress in other people, such as increases in breathing rate. This triggers a cascade of our own stress hormones, Heidi Hanna, executive coach and author of Stressaholic, told us. And you don’t need to be in the same room to catch someone else’s stress, which is transmittable via email, texts and social media. (Curt responses could signal someone is under a tight deadline, for example.) When you feel stressed, take breaks and get enough sleep – that’s not selfish. It benefits everyone around you.

Itching

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If you’ve seen someone else scratch an itch and suddenly felt your own skin tingle, you aren’t alone. A study in the journal Science found that mice started scratching themselves when they looked at chronically itchy rodents. In fact, the normal mice near their extra-itchy counterparts ended up scratching twice as often as usual.

Desire for new things

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It’s no coincidence you suddenly want a new car after your friend’s visit to the dealership. A 2012 study in the Journal of Neuroscience found that participants rated objects as more valuable when they thought someone else wanted them. “I call this wedding-band syndrome,” psychologist Elizabeth Lombardo, PhD, tells Prevention. “A man is more attractive if someone already wants him – he must be worth having.” Shut the green-eyed monster down by reminding yourself of how thankful you are for what you already own.

Weight loss

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A study in the journal Obesity found that when volunteers started a weight-loss program, their partners dropped kilos at about the same rate as them. Use the ripple effect to your advantage by enlisting your partner to join you on your weight-loss journey.

Loneliness

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You’d think distance would keep lonely people from spreading their isolation, but the opposite is true, according to a study in the Journal of Personality and Social Psychology. The findings suggested that after someone started feeling lonely, others in that person’s social group would get lonelier over time, too. The feeling acted like a contagion, rather than a result of lonely people being attracted to other lonely people. The researchers believe groups tend to blow off lonely people, which keeps the cycle going. Nip the cycle in the bud by getting in touch with friends you haven’t heard from in a while.

Divorce

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A 2013 study in the journal Social Forces found that friends of divorcees were 75 percent more likely to get a divorce than someone whose friends were still married. When a friend of a friend got divorced, married couples were 33 percent more likely to split. The study authors suggest that helping friends work out their relationship issues could strengthen your own relationship, too. The results also found that married people with the most friends were the least likely to break up, so try expanding your social network while supporting friends in rocky relationships.

Body quirks

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Yawning, laughing, itching, coughing, vomiting and crying are all socially contagious. Yawning is so infectious, says psychologist Robert R. Provine, author of Curious Behaviour, that we yawn when we see, hear, or even read about someone else doing it. “We are often herd animals, not in full conscious control of our behaviour,” he says. Scientists theorise that sharing these quirks conferred an evolutionary advantage: Laughter is a form of bonding; scratching an itch, a safety precaution. (Your brain may think, Hey, their fleas could jump ship and infest me.) Yawning could be how cavemen ancestors synchronised their sleep-wake schedules.